1. Field of the Invention
The present invention generally relates to the field of electrical circuits and systems. More particularly, the invention relates to circuits and systems for power management.
2. Background Art
Electronic devices, such as cellular phones, MP3 players, portable digital assistants (PDAs), and other mobile electronic devices, typically include a power management unit (PMU) for integrating various power-related functions, such as battery charging from a computer USB port or an AC power adaptor or supplying power to a USB On-The-Go (OTG) device, such as a USB hard drive, backlight LEDs, or a camera flash. In addition to the above functions, a typical PMU in an electronic device, such as a cellular phone, MP3 player, or PDA, also provides the device's system power, which may originate from, for example, the device's internal battery, a USB port on a computer, or an AC power adaptor.
To provide the above power-related functions in an electronic device, such as a mobile electronic device, a conventional PMU typically includes a separate circuit for each function. For example, the conventional PMU can include a buck-boost circuit for converting a battery voltage to a required system voltage. The conventional PMU can further include battery charger circuits for charging the electronic device's battery from an external power source, such as an AC power adaptor, USB port on a computer, or USB OTG device. The conventional PMU can further include circuits for providing power to backlight LEDs, which can illuminate a liquid crystal display (LCD), and a camera flash LED. In the conventional PMU, the aforementioned circuits typically include a number of distinct and separate inductors and one or more controllers. As a result, the conventional PMU can consume an undesirable amount of limited space in an electronic device, such as a mobile electronic device.